Infrasense Uses GPR to Measure Pavement Density in New Hampshire and Maine

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Infrasense has recently participated in pavement density investigations of new asphalt in New Hampshire, Maine, and California using its proprietary software for measuring and mapping pavement density with Ground Penetrating Radar (GPR). GPR provides complete coverage of a new asphalt pavement, and can be used to map areas of relatively higher or lower density within the pavement.

Infrasense vehicle-mounted GPR system for pavement density

Infrasense, Inc. has recently completed asphalt pavement density measurements and mapping for a new pavement project in New Hampshire and a technology demonstration for the Maine DOT using ground-penetrating radar (GPR). Achieving the target density for a pavement is particularly important for long term pavement performance. Pavement density is a measure of Quality Control and Quality Assurance (QC/QA) of new pavement construction projects. Traditionally, density has been measured using cores or nuclear density gauges. However, these methods provide data at only a limited number of random locations, and working with nuclear gauges can require special licensing. The GPR-based system developed by Infrasense provides 100% coverage of the entire pavement on-site, revealing potential patterns of low density, such as along joints and at stopping points. The system has previously been implemented by the Florida DOT and Minnesota DOT.

Infrasense’s GPR system for pavement density measurement consists of a single or dual air-coupled radar antenna (s) mounted to the front or back of a survey vehicle. The GPR data is collected in a series of lines spaced 2 feet transversely across the width of the pavement, with each line representing a cross sectional slice of the pavement at a particular offset. Infrasense integrated a photo-reflective laser switch into the system to automatically insert marks in the GPR data for the start and end of the section being surveyed. Infrasense modified the antenna settings to enhance the near-surface resolution of the data and to collect data more frequently than traditional GPR surveys. In order to assess the pavement on-site, Infrasense developed processing software (GPRQA) that automatically analyzes the GPR field data to produce color contour maps of the asphalt surface dielectric, which is proportional to the density. The analysis can be carried out on site or in the office. By analyzing these maps on-site for stronger and weaker dielectrics, cores can be taken at optimum locations for calibration.

The purpose of the New Hampshire pavement project was to provide asphalt pavement density data across 2 driving lanes and 2 shoulders over a 4-mile stretch of new pavement constructed using both Intelligent Compaction (IC) and conventional paving methods. The results of the GPR testing were used to locate density variations between the IC half of the section and the conventionally-paved half of the section, and to locate other spatial variations within each half. Infrasense correlated the GPR results to the pavement density using test cores from the standard QA/QC procedure, as well as additional cores selected strategically using the GPR map results.

Infrasense has also recently provided data analysis expertise for pavement density projects using GPR in Maine and California. In Maine, Infrasense provided GPR data analysis for a 1500-foot section of I-95 that was surveyed by Maine DOT personnel using their own GPR system. The results were mapped using GPRQA and results were correlated with density information obtained from cores taken every 50 feet during previous Falling Weight Deflectometer (FWD) testing. Infrasense also recently performed data analysis using its proprietary GPRQA software for a pavement density investigation in California.

About Infrasense, Inc.

Since 1987, Infrasense, Inc. has applied the most current technologies to the most difficult challenges in subsurface scanning. Infrasense’s engineers are able to nondestructively extract critical information from a diverse range of structures. The firm has conducted research to advance the field of subsurface detection, while also providing valuable information to clients across the country. Learn more about Infrasense, Inc. and its services at

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Sarah Kelly
Infrasense, Inc.
(781) 648-0440
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